Oxidation resistant polymeric compositions

ABSTRACT

Antioxidants such as the reaction product of p-aminodiphenylamine and glycidyl methacrylate [3-N-(4&#39;-anilinophenyl)amino-2-hydroxypropyl methacrylate], and the reaction product of n-hexyl-N&#39;-phenyl-p-phenylenediamine and glycidyl methacrylate [3-[N-(4&#39;-anilinophenyl)-N-(1,3-dimethylbutyl)]amino-2-hydroxypropyl methacrylate], age resistant polymers having monomeric age resistors physically combined therewith and oxidation resistant polymeric compositions prepared by free radical polymerization techniques involving the use of said antioxidants as monomers.

This is a division of Applicaton Ser. No. 153,446 filed June 15, 1971,and issued June 18, 1974, as U.S. Pat. No. 3,817,916.

This invention relates to monomeric antioxidants, oxidation resistantpolymeric compositions and processes for preparing said monomericantioxidants and oxidation resistant compositions. More particularly,the invention relates to a process of preparing polymeric compositionscontaning antioxidants which are not susceptible to solvent extractionand which are resistant to volatilization.

Essentially all types of rubber, both natural and synthetic, andparticularly rubbers formed from dienes, are known to be susceptible todeterioration resulting from prolonged exposure to oxidative aging. Agreat deal of effort has been expended by those engaged in the field ofpolymer technology to develop various stabilizers that will effectivelyinhibit the adverse effects of aging of polymeric compositions.Unfortunately, many of the commercially accepted stabilizers may bevolatilized when the polymeric products are exposed to elevatedtemperatures and/or high vacuum over prolonged periods of time.Furthermore, they are rather quickly extracted from polymericcompositions by repeated washings with aqueous detergent solutions ororganic solvents. These severe conditions are routinely encountered bygarments containing latex treated fabric when they are subjected tofrequent laundering or dry-cleaning.

It is, therefore, an object of this invention to provide a process forpreparing oxidation resistant polymeric compositions. A further objectof this invention is to provide a process of preparing polymericcompositions that are highly resistant to oxidative aging at elevatedtemperatures even after repeated exposure to aqueous detergent solutionsor dry-cleaning fluids. It is still further object of this invention toprovide a process of preparing polymers possessing antioxidantschemically bound thereto.

In accordance with the present invention oxidation resistant polymericcompositions are prepared by polymerizing a monomeric amine antioxidantwith one or more comonomers.

The amine antioxidants of the present invention have the followingstructural formula. ##EQU1## wherein R is selected from the groupconsisting of alkyl radicals having 1 to 12, preferably 3 to 12, carbonatoms, cycloalkyl radicals having 5 to 12 carbon atoms, aralkyl radicalshaving 7 to 24 carbon atoms and aryl radicals having 6 to 24 carbonatoms wherein R¹ and R² are selected from the group consisting ofhydrogen and alkyl groups having 1 to 4 carbon atoms and wherein R³ isselected from the group consisting of hydrogen, alkyl radicals having 1to 12 (preferably 1 to 8) carbon atoms, cycloalkyl radicals having from5 to 12 carbon atoms, and aralkyl radicals having 7 to 24 carbon atoms,preferably a benzyl or α-phenethyl radical wherein R⁴, R⁵, R⁶, R⁷, andR⁸ are selected from the group consisting of hydrogen and alkyl radicalshaving from 1 to 4 carbon atoms, i.e. methyl, ethyl, propyl, and butylradicals, the sum of the carbon atoms in R⁴ and R⁵ preferably being 4 orless, and the sum of carbon atoms in R⁷ and R⁸ preferably being 4 orless; wherein R⁹ is selected from the group consisting of hydrogen;alkyl radicals having from 1 to 4 carbon atoms, i.e., methyl, ethyl,propyl, and butyl radicals; carboxymethyl radical and carbalkoxymethylradicals; and wherein R¹⁰ is selected from the group consisting ofhydrogen; alkyl radicals having from 1 to 4 carbon atoms, i.e., methyl,ethyl, propyl, and butyl radicals; phenyl and substituted phenylradicals, e.g., a phenyl group having located in the para position, analkyl radical having 1 to 4 carbon atoms such as methyl, or an alkoxyradical having 1 or 2 carbon atoms, e.g., methoxy; carboxyl radical andcarbalkoxy radicals.

Preferably --NH--R is in the para position.

Under structural formula (I), the carbalkoxymethyl radicals preferablyhave the following structural formula: ##EQU2## wherein R¹¹ is an alkylradical having from 1 to 4 carbon atoms. The carbalkoxy radicalspreferably have the following structural formula: ##EQU3## wherein R¹²is an alkyl radical having from 1 to 4 carbon atoms.

In structural formula (I), preferably R⁹ is hydrogen or methyl.Preferably R¹⁰ is hydrogen. In structural formula (II), R¹¹ ispreferably methyl or ethyl. In structural formula (III), R¹² ispreferably methyl or ethyl.

The amine age resisters of the present invention are illustrated by thefollowing compounds.

3'-(4"-anilino anilino)-2'-hydroxypropyl methacrylate

3'-N-(4"-anilinophenyl)amino- 2'-hydroxy-1'-methylpropyl methacrylate

3'-N-(4"-anilinophenyl)amino- 2'-hydroxy-1', 2', 3'-trimethylpropylmethacrylate

3'-N-(4"-anilinophenyl)amino- 2'-hydroxy-1', 1'-di-n-butylpropylmethacrylate

3'-N-(4"-anilinophenyl)amino- 2'-hydroxypropyl acrylate

3'-N-(4"-anilinophenyl)amino- 2'-hydroxypropyl-2-methoxy methacrylate

3'-N-(4"-anilinophenyl)amino- 2'-hydroxypropyl-2-carboxy methacrylate

3'-N-(4"-anilinophenyl)amino- 2'-hydroxypropyl-3-phenyl methacrylate

3'-N-(4"-anilinophenyl)amino- 2'-hydroxypropyl-3-methoxy methacrylate

3'-N-(4"-anilinophenyl)amino- 2'-hydroxypropyl-3-(4-carboxy phenyl)methacrylate

3'-N-(4"-anilinophenyl)amino- 2'-hydroxypropyl-3-(4-carbmethoxy phenyl)methacrylate

3'-N-(4"-anilinophenyl)-N-isopropylamino-2'-hydroxypropyl methacrylate

3'-N-(4"-anilino-3"-methylphenyl)amino- 2'-hydroxypropyl methacrylate

3'-N-(4"-anilino-3"-cyanoethylphenyl)amino-2'-hydroxypropyl methacrylate

3'-N-(4"-anilino-2"-tolylphenyl)amino- 2'-hydroxypropyl methacrylate

3'-N-(4"-anilino-2"-cyclohexylphenyl)amino- 2'-hydroxypropylmethacrylate

3'-N-(4"-anilino-2"-benzylphenyl)amino- 2'-hydroxypropyl methacrylate

3'-N-[4"-(2"-methylanilino)phenyl] amino-2'-hydroxypropyl methacrylate

3'-N-[4"-(2"-cyanomethylanilino)phenyl]amino-2'-hydroxypropylmethacrylate

3'-N-[4"-(2"-tolylanilino)phenyl] amino-2'-hydroxypropyl methacrylate

3'-N-[4"-(4"-cyclohexylanilino)phenyl] amino-2'-hydroxypropylmethacrylate

3'-N-[4"-benzylanilino)phenyl] amino-2'-hydroxypropyl methacrylate

When polymerized, the amine antioxidants of the present invention formsegmers having the following structural formula. ##EQU4##

The monomeric antioxidants can easily be prepared by dissolving theaforementioned amines in a solvent such as benzene, adding a phenol orphenolate catalyst, such as sodium or potassium phenolate, and thenslowly adding the epoxy compound. Preferably the reaction composition isheated and stirred for several hours, for example at 50°C. to 60°C. for2 hours. The solvent is then removed, e.g., by a rotary evaporator.

The amine age resisters which are used within the practice of thepresent invention can be prepared by reacting (A) at least one aminecompound as described hrereinafter with at least one epoxy compoundhaving the following structural formula: ##EQU5##

Representative epoxy compounds which can be used to prepare themonomeric age resisters of the present invention are:

Glycidyl methacrylate

Glycidyl-3-methyl methacrylate

Glycidyl-3-phenyl methacrylate

Glycidyl-3-n-butyl methacrylate

Glycidyl-3-cyclohexyl methacrylate

Glycidyl acrylate

Glycidyl crotonate

Glycidyl-3-n-butyl acrylate

Glycidyl cinnamate

Glycidyl-3-cyclohexyl acrylate

Glycidyl-2-n-propyl acrylate

Glycidyl-2-n-butyl acrylate

The epoxy compounds can be prepared by the reaction of epichlorohydrinwith a carboxylic acid in the presence of a base.

The amine compounds which can be reacted with the aforementioned epoxycompounds to prepare the amine age resisters of the present inventionconform to the following structural formula. ##SPC1##

In preparing the amine antioxidants of the present invention,consideration should be given to the activities of the R--NH-- and R³--NH-- groups with epoxy groups. If one amine group is more reactivewith epoxy groups than the other amine group, there is a greaterpossibility that the amine reactant will react with one, rather than twoepoxy groups. The activity of the amine groups is dependent upon thenature of the R and R³ radicals. Normally amine groups possessing alkylor aralkyl substituents are more reactive than amine groups containingaryl substituents. Amine groups possessing large substituents aregenerally less reactive with epoxy groups than amine groups containingsmaller substituents.

Representative amine compounds which can be used to prepare themonomeric age resisters of the present invention are:

N,n' -dimethyl-p-phenylenediamine

N,n' -di-beta-naphthyl-p-phenylenediamine

N,n' -bis(1-ethyl-3-methylpentyl)-p-phenylenediamine

N,n' -bis(1-methylheptyl)-p-phenylenediamine

N,n' -bis(sec.butyl)-p-phenylenediamine

N-phenyl-N' -beta-hydroxyethyl-p-phenylenediamine

N-phenyl-N' -cyanoethyl-p-phenylenediamine

N-sec.butyl-N' -cyanoethyl-p-phenylenediamine

N-beta-naphthyl-N' -sec.)butyl-p-phenylenediamine

N,n' -diphenethyl-p-phenylenediamine

N-methyl-N' -phenyl-p-phenylenediamine

N-ethyl-N' -phenyl-p-phenylenediamine

N-isopropyl-N' -phenyl-p-phenylenediamine

N-sec.butyl-N' -phenyl-p-phenylenediamine

N-cyclohexyl-N' -phenyl-p-phenylenediamine

N-1,3-dimethylbutyl-N' -phenyl-p-phenylenediamine N-1-methylheptyl-N'-phenyl-p-phenylenediamine

N-phenethyl-N'-phenyl-p-phenylenediamine

N-benzyl-N' -phenyl-p-phenylenediamine

A particularly representative amine is p-aminodiphenylamine.

Para-aminodiphenylamine and the rest of the amine compounds which can beused to prepare the monomeric antioxidants of the present invention areknown in the prior art and can be prepared by well known prior artmethods. U.S. Pat. NO. 2,381,015; U.S. Pat. No. 3,209,030 and BritishPat. No. 1,064,958 illustrate some prior art methods.

The aforementioned monomeric antioxidants may be polymerized by wellknown free radical polymerization techniques with one or more comonomersthat are known to polymerize in free radical initiated polymerizationsystems. The polymerization may be carried out in emulsion, suspension,bulk or solution type systems. Some adjustments in the polymerizationrecipe and/or conditions may be necessary to obtain a satisfactory rateof polymer formation, depending on the amount of monomeric antioxidantincluded and the other monomers involved. Adjustments which may benecessary in the polymerization conditions to improve polymerizationrates include increasing the temperature of polymerization and/orincreasing the initiator level and/or increasing the level of activatoringredients. Solvents may also be required to obtain adequate solubilityof the monomers with each other as well as to solubilize otheringredients where required. Some solvents, such as methyl ethyl ketoneor isopropyl alcohol, can be used to advantage with an emulsionpolymerization system. These adjustments, where necessary, are tocounteract the inhibitory effect of the monomeric antioxidant and toinsure its solubility in the system.

Examples of free initiators that are useful in the practice of thisinvention are those known as "Redox" initiators, such as appropriatecombinations of chelated iron salts, sodium formaldehyde sulfoxylate andorganic hydroperoxides such as cumene and paramenthane hydroperoxides.Other initiators such as azoisobutyronitrile, benzoyl peroxide, hydrogenperoxide and potassium persulfate may also be used, depending on theparticular polymerization system.

The special monomers used in the practice of this invention have certainchemical characteristics which preclude their use in polymerizationprocesses other than those initiated by free radicals. By "free radicalinitiated systems" is meant systems wherein free radicals are generatedby any of various processes such as thermal decomposition of variouspersulfate, perborate, peroxide, azo or azonitrile compounds; induced(catalytic or "Redox" promoted) decomposition of various persulfate,peroxide or hydroperoxide compounds and generation of free radicals byexposure of the system to high energy radiation such as radiation from aradioactive source or ultraviolet light. Such systems are very wellknown in the art and are widely used commercially, e.g., in thepreparation of SBR, styrene/butadiene copolymers.

The most widely used system for preparation of elastomeric polymers,i.e., polymers prepared from a monomer charge made up of at least 40percent diene, preferably at least 60 percent diene, by free radicalinitiation is the emulsion system. Polymers ranging all the way fromliquid, low molecular weight* (mol wts of about 1,000 to 5,000) topolymers of (molecular weight (60,000 to 70,000 and higher) to oilextendable, at least 50 percent soluble, rubbery solid, high molecularweight (100,000 to 500,000 or more) and even highly gelled, less than 50percent soluble, may be prepared by emulsion polymerization. Themonomeric age resisters of the present invention can be used in suchemulsion polymerization systems to produce polymers of theaforementioned type.

The principles of emulsion polymerization are discussed in referencessuch as "Synthetic Rubber" by G. S. Whitby, Editor-in-Chief, John Wileyand Sons, 1954, particularly Chapter 8, and "Emulsion Polymerization" byF. A. Bovey et al, Vol IX of "High Polymers," Interscience PublishersInc. 1955. Some specialized applications of these principles areindicated in U.S. Pat. Nos. such as 3,080,334; 3,222,334; 3,223,663;3,468,833 and 3,099,650.

Very effective as free radical polymerization initiators used within thepractice of the present invention, when used under appropriateconditions, are compounds such as t-butyl hydroperoxide and paramenthanehydroperoxides, and even hydrogen peroxide. These compounds perform veryeffectively when used in polymerization recipes containing appropriatelevels of supporting ingredients. By "supporting ingredients" is meantthose materials often referred to as activators in emulsion, or othersystems, where required. U.S. Pat. No. 3,080,334 describes some of thesematerials at column 5, lines 20- 26. Such materials can also be referredto as catalyst activators. The term "Redox Polymerization" is often usedwhere the complete initiation system includes a Redox system, i.e.,reducing agents and oxidizing agents in a proportion that yieldspolymerization initiating species. All of these initiator systems arewell known in the art.

Emulsion and suspension polymerizations are normally accomplished in therange of 5°C. to 90°C. while the temperature range for solution or bulkpolymerizations is normally 20°C. to 150°C. Though the activated or"Redox" initiated systems are preferred for low temperaturepolymerizations, they are very effective at high temperatures also,normally requiring appreciably lower quantities of the variousingredients to obtain a desirable polymerization rate.

The free radical sources used in the initiator systems are thosecustomarily used in free radical polymerizations, for example, organicinitiators such as azo-nitriles, azo-derivatives, peroxides, andhydroperoxides and inorganic initiators such as inorganic peroxycompounds. Radiation, e.g., of the ultra-violet and gamma type can alsobe used as a free radical source. Various organic initiators aredescribed by J. Brankrup and E. H. Immergut, Polymer Handbook (JohnWiley and Sons), 1965, pages II-3 to II-51. Peroxide initiators includethe aralkyl, aliphatic, aliphatic acyl, aromatic acyl, ketone, aldehydeand perester types. Hydroperoxide compounds include aralkyl andaliphatic hydroperoxides. Inorganic peroxy compounds includepersulfates, perborates, perphosphates and hydrogen peroxide.

Aralkyl peroxides are represented by dicumyl peroxide; aliphaticperoxides by di tert.butyl peroxide; aliphatic acyl peroxides by acetylperoxide, decanoyl peroxide and lauroyl peroxide; aromatic acylperoxides by benzoyl peroxide and 2,4-di-chlorobenzoyl peroxide; ketoneperoxides by methylethyl ketone peroxide and cyclohexanone peroxide;aldehyde peroxides by heptaldehyde peroxide; and perester peroxides bytert.butyl peracetate, tert.butyl perpivalate and tert.butylperbenzoate. Aralkyl hydroperoxides are represented by cumenehydroperoxide and diisopropylbenzene hydroperoxide and aliphatichydroperoxides by tert.butyl hydroperoxide and paramenthanehydroperoxide. Persulfate, perborate and perphosphate compounds arerepresented by the sodium, potassium and ammonium persulfates,perborates and perphosphates; azo-nitriles and azo-derivatives by2,2'-azo-bis-isobutyronitrile, 2,2'-azo-bis-2-methylpropionitrile andazo-bis-diphenylmethane.

Supporting ingredients, i.e., activators capable of activating certaininitiators to produce free radicals include iron compounds such asferrous sulfate or cobalt compounds, complexed with compounds such assodium salts of ethylene diamine tetra acetic acid or sodium orpotassium pyrophosphate. Reducing agents used in Redox systems includesodium formaldehydesulfoxylate, various sugars and hydrosulfites.

Various initiator system components are described column 4, lines 14 to;b 32, in U.S. Pat. No. 3,080,334.

Examples of comonomers that are useful in the practice of this inventionin combination with the monomeric antioxidants are polymerizableunsaturated hydrocarbons, both substituted and unsubstituted, includingconjugated diene monomers, such as butadiene-1,3; 2-chlorobutadiene-1,3;isoprene; 2-ethyl-butadiene-1,3; piperylene; and hexadienes andcopolymerizable monoolefins including vinyl and vinylidene monomers suchas styrene, α-methylstyrene, divinyl benzene, vinyl chloride, vinylacetate, vinylidene chloride, methylmethacrylate, ethylacrylate, thevinylpyridines including 2-vinyl pyridine, 5-methyl-2-vinylpyridine,4-vinyl pyridine and 2 -vinyl-5-ethyl pyridine, acrylonitrile,methacrylonitrile, methacrylic acid and acrylic acid. Mixtures of themonomeric antioxidants and mixtures of the comonomers may be used. Themonomer charge weight ratio is normally from about 0.10/99.9 to about10/90 or even 20/80 monomeric antioxidant/comonomer. The ratio may evenbe as high as 30/70 or 60/40. A charge ratio of about 0.5/99.5 to about5.0/95 is preferred. Ratios will vary depending on the amount ofantioxidant desired to be bound and on the reactivity ratios of themonomers in the particular polymerization system used. However, theratio may be even higher and the monomeric antioxidant may evenconstitute all of the monomer charged, i.e., the ratio can be 100/0.

Preferably the monomer system contains at least 50 parts by weight per100 parts by weight of total monomer of at least one diene, preferably aconjugated diene, such as 1,3-butadiene or isoprene. It always containsat least 40 parts by weight of said diene.

One embodiment of the present invention involves the use of a monomersystem comprised of from about 50 to about 99.9 parts of at least onediene monomer, preferably a conjugated diene, 0 to about 49.9 parts ofat least one monomer selected from the group consisting of vinylmonomers and vinylidene monomers and from about 0.10 to 5.0 parts byweight of at least one monomeric antioxidant, all parts being parts byweight per 100 parts by weight of total monomer. Preferably at least 0.5part of monomeric antioxidant is used. When at least 0.5 part of themonomeric antioxidant is used, the upper limit on the diene monomerrange is 99.5 parts and the upper limit of the vinyl monomer and/orvinylidene monomer range is 49.5 parts. The upper limit of the monomericantioxidant range may be even higher than 5.0, i.e., 10, 20, 30 and even50.

The polymers resulting from the free radical polymerizations ofmonomeric systems containing the monomeric antioxidants of the presentinvention have a special advantage in that the age resistant portion isnot extractable, and therefore the polymeric compositions are highlyresistant to oxidative aging even after repeated exposure to aqueousdetergent solutions or dry-cleaning fluids. This feature is especiallysignificant where polymers are used in foam backings for rugs and wherepolymers are used in solution or latex form to treat fabrics, since suchproducts are often exposed to aqueous detergent solutions ordry-cleaning fluids. This feature is also significant where factors suchas contact with lubricating oils or exposure to high vacuum conditionsare a consideration.

One of the advantages of the present process is that it permits thepreparation of polymers prepared from monomer systems containing dienemonomers and containing built-in-stabilizers, without the formation ofappreciable gel, that is, polymers can be made which are essentiallygel-free. Gel formation is generally undesirable in a polymer since itcan cause processing difficulties and directly and/or indirectly canaffect affect physical properties of the polymer in its vulcanized form.Normally a macro gel content of less than 50 percent is desirable.Preferably a gel content of less than 10 percent is desirable. Mostpreferably a gel content below 5 percent is desirable. Gel is the amountof polymer that is insoluble in an organic solvent such as benzene. Oneway to measure gel content comprises placing about 0.20 to about 0.30grams of the polymer in 100 milliliters of benzene and permitting themixture to stand for 48 hours. The mixture is then filtered through a100 mesh stainless steel wire cloth having a wire diameter of 0.045inch. A solids is then run on the filtrate to determine the amount ofsoluble polymer. The amount of gel is the difference between the amountof polymer placed in the benzene originally and the amount of solublepolymer. The percent gel is one hundred times the gel weight divided bythe original polymer weight.

To afford adequate protection against degradation the polymers shouldcontain from about 0.10 part to about 10.0 parts by weight of thesegmeric form of the monomeric antioxidant per 100 parts by weight ofthe polymer, although from about 0.50 part to about 5.0 parts isnormally satisfactory, from about 0.50 part to about 3.0 parts beingpreferred. As much as 20 parts, 30 parts, 50 parts and more of thepolymer may consist of the antioxidant segmeric unit while the lowerlimit may be 0.50 part to 0.10 part and lower. In fact, polymerscontaining 100 percent antioxidant segmeric units may be produced, ifdesired. However, as the amount of bound antioxidant increases thephysical characteristics of the polymer are altered accordingly. Whereit is desired to produce a polymer which is self stabilizing and whichsubstantially retains the physical properties of the comonomer orcomonomers, normally the polymer should contain no more than about 10.0parts by weight of the antioxidant segmeric unit, i.e., repeat unit.Such polymers preferably are solid, although they may be liquid. Whereit is desired that the polymer act as a polymeric antioxidant which maybe blended with unstabilized polymers the polymer should normallycontain greater amounts of the monomeric antioxidant. The remainder ofthe polymer is comprised preferably of the segmeric form of at least oneconjugated diene monomer and/or the segmeric form of at least one vinylmonomer. Preferably the polymers contain at least 50 percent by weightof the segmeric form of a diene, preferably a conjugated diene such asbutadiene-1,3 or isoprene. Most preferred are polymers containing fromabout 50 to about 99.9 parts by weight of the segmeric form of at leastone diene, preferably a conjugated diene, 0 to about 49.9 parts byweight of the segmeric form of at least one monomer selected from thegroup consisting of vinyl monomers and vinylidene monomers and 0.10 to5.0 parts by weight of the segmeric form of at least one monomericantioxidant, all parts being by weight per 100 parts by weight ofpolymer. Preferably the polymer contains at least 0.5 part of thesegmeric form of the monomeric antioxidant. When the polymer contains atleast 0.5 part of the segmeric form of the monomeric antioxidant, theupper limit of diene segmer range is 99.5 parts and the upper limit ofthe vinyl segmer and/or vinylidene segmer range is 49.5 parts. The upperlimit of the segmeric form of the monomeric antioxidant range may beeven higher than 5.0, i.e., 10, 20, 30 and even 50. In all instances thepolymers must contain at least 40 parts by weight of the segmeric formof a diene monomer, preferably a conjugated diene. In polymers generallyprepared by free radical, particularly emulsion techniques, thetrans-1,4 content is generally greater than the cis-1,4 or 1,2 content.

All of the monomeric amine antioxidants described herein are capable ofstabilizing polymers by simple incorporation into the polymers byconventional techniques such as by addition to polymer latices or byaddition to the solid polymer on a mill or in a Banbury. When blending aself-stabilizing polymer with other polymers, especially when theself-stabilizing polymer contains large amounts of the segmeric form ofthe monomeric antioxidant, one must consider the solubility problemsinvolved in blending dissimilar polymers.

Polymers subject to deterioration by oxidation that can be convenientlyprotected by the antioxidants described herein include substituted andunsubstituted, saturated and unsaturated, natural and syntheticpolymers. The oxidizable natural polymers include rubber in its variousforms, e.g., pale crepe and smoked sheet, and balata and gutta percha.The oxidizable synthetic polymers are prepared from a single monomer(homopolymer) or a mixture of two or more copolymerizable monomers(copolymers) wherein the monomers are combined in a random distributionor block form. The monomers may be substituted or unsubstituted and maypossess one or more double bonds, for example, diene monomers, bothconjugated and nonconjugated, and monoolefins including cyclic andacyclic monoolefins, especially vinyl and vinylidene monomers. Examplesof conjugated dienes are 1,3-butadiene, isoprene, chloroprene,2-ethyl-1,3-butadiene, 2,3-dimethyl-1,3-butadiene and piperylene.Examples of nonconjugated dienes are 1,4-pentadiene, 1,4-hexadiene,1,5-hexadiene, dicyclopentadiene, 1,5-cyclooctadiene and ethylidenenorbornene. Examples of acyclic monoolefins are ethylene, propylene,1-butene, isobutylene, 1-pentene and 1-hexene. Examples of cyclicmonoolefins are cyclopentene, cyclohexene, cycloheptene, cyclooctene and4-methyl-cyclooctene. Examples of vinyl monomers are styrene,acrylonitrile, acrylic acid, ethylacrylate, butylacrylate, methyl vinylether, vinyl acetate and vinyl pyridine. Examples of vinylidene monomersare α-methylstyrene, methacrylic acid, methyl methacrylate, ethylmethacrylate, glycidyl methacrylate and vinylidene chloride.Representative examples of the synthetic polymers used in the practiceof this invention are polychloroprene; homopolymers of a conjugated1,3-diene such as isoprene and butadiene, and in particular,polyisoprenes and polybutadienes having essentially all of their repeatunits combined in a cis-1,4 structure; copolymers of a conjugated1,3-diene such as isoprene and butadiene with up to 50 percent by weightof at least one copolymerizable monomer including ethylenicallyunsaturated monomers such as styrene or acrylonitrile; butyl rubber,which is a polymerization product of a major proportion of a monoolefinand a minor proportion of a multiolefin such as butadiene or isoprene;polyurethanes containing carbon to carbon double bonds; and polymers andcopolymers of monoolefins containing little or no unsaturation, such aspolyethylene, polypropylene, ethylene propylene copolymers andterpolymers of ethylene, propylene and a nonconjugated diene such asdicyclopentadiene, 1,4-hexadiene, ethylidene norbornene and methylenenorbornene.

When added in free form normally 0.001 to 10.0 percent of theantioxidant by weight, i.e., parts by weight based on the weight of thepolymer, i.e., 100 parts by weight of the polymer can be used, althoughthe precise amount of the antioxidant which is to be employed willdepend somewhat on the nature of the polymer and the severity of thedeteriorating conditions to which the polymer is to be exposed. Inunsaturated polymers such as those made from conjugated dienes, theamount of antioxidant necessary is greater than that required by asaturated polymer such as polyethylene. It has been found that aneffective antioxidant amount of the disclosed stabilizers in rubberyunsaturated polymers will generally range from 0.05 to 5.0 percent byweight i.e., parts by weight based on the weight of the polymer,although it is commonly preferred to use from 0.5 to 3.0 percent byweight, i.e., parts by weight based on the weight of the polymer.Mixtures of the antioxidants may be used.

The following examples illustrate the practice of the present invention.Unless otherwise indicated, all parts are parts by weight.

EXAMPLE 1

Para-aminodiphenylamine (62.5 grams/0.34 mole) was dissolved in 670 ml.of benzene. The catalyst was prepared by adding one gram of sodiumhydroxide and one gram of phenol to 5 ml. of water. Five milliliters ofethanol was added to insure solubility in the benzene. After adding thecatalyst, 24 grams (0.169 mole) of glycidyl methacrylate was addedslowly from a dropping funnel and the mixture was stirred for 18 hoursat room temperature. The solvent was then removed with a rotaryevaporator. The yield was 55 grams (93%). The melting point of theproduct was 126° C.

EXAMPLE 2

Ninety-one grams (0.34 mole) ofN-1,3-dimethylbutyl-N'-phenyl-phenylenediamine were dissolved in 670milliliters of benzene. Catalyst was prepared and glycidyl methacrylatewas added as described above. The yield was 58 grams (84%).

Examples 1 and 2 were run using a 2/1 molar ratio of amine tomethacrylate. A 1/1 molar ratio can be used to produce essentially thesame products.

The following examples illustrate the preparation of polymers containingmonomeric antioxidants as part of the polymeric chain. They alsoillustrate the oxidation resistance possessed by said polymers. Unlessotherwise indicated all parts are parts by weight.

EXAMPLES 3 to 7

The following polymerizations were carried out using the followingrecipes.

                                      Table III                                   __________________________________________________________________________    Order of             Examples (parts)                                         Addition Ingredients 12    13     14    15    16                              __________________________________________________________________________          Water          194   200    194   195   195                                   Potassium soap of                                                             disproportionated                                                             rosin acids    2.8   2.7    2.7   2.7   2.7                                   Sodium soap of tallow                                                         fatty acids    2.4   2.4    2.4   2.4   2.4                             1     Trisodium phosphate                                                                          --    .375   .04   .375  .375                                  Sodium hydrosulfite                                                                          --    --     --    .011  .009                                  Sodium salt of condensed                                                      naphthalene sulfonic                                                          acid           .08   .08    .15   .08   .08                                   Tripotassium phosphate                                                                       .25   --     --    --    --                                    Styrene        20    --     20    20    20                              2     Acrylonitrile  --    30     --    --    --                                    Tertiary dodecyl mercaptan                                                                   .25   .60    .30   .40   .30                                   Monomeric antioxidant.sup.(1)                                                                1.25  1.25   5.0   1.25  1.25                            3     Methyl ethyl ketone                                                                          55    55     --    55    44                                    Cyclohexanone  --    --     45    --    --                              4     Butadiene-1,3  75    67     75    75    75                                    Water          5     11     5     11    11                                    Chelating agent.sup.(2)                                                                      .077  .038   .077  .038  .023                            5     Ferrous sulfate heptahydrate                                                                 .02   .0075  .02   .009  .02                                   Sodium formaldehyde                                                           sulfoxylate    .04   .10    .02   .08   .05                                   Sodium hydrosulfite                                                                          .01   .006   .01   .002  .004                                  Styrene        2.4   --     2.4   2.4   2.4                             6     Acrylonitrile  --    2.4    --    --    --                                    Paramenthane hydroperoxide                                                                   .04   .05    .02   .02   .01                             __________________________________________________________________________    Polymerization temperature (°F.)                                                            41    77     45    70    122                             Polymerization time (hours)                                                                        13    19     10    10    12                              Percent conversion   65    79     65    66    60                              __________________________________________________________________________     .sup.(1) Approximately 1/1 (molar ratio) reaction product of glycidyl         methacrylate and p-aminodiphenylamine, the major component being              3-N-(4'-anilinophenyl)amino-2-hydroxypropyl methacrylate. The antioxidant     was dissolved in 3.54 parts of methyl ethyl ketone before being added to      the system.                                                                   .sup.(2) 90/10 mixture of tetrasodium salt of ethylene diamine tetraaceti     acid and monosodium salt of N,N-di(α-hydroxyethyl) glycine.        

The above polymerization systems were shortstopped with 0.10 part ofsodium dimethyldithiocarbamate and 0.05 part of diethylhydroxylamine in4.4 parts of water. A very small amount of sulfuric acid was added to atleast one number 5 solutions to dissolve any ferrous hydroxide formed.

EXAMPLES 17, 18 and 19

The following recipe (Table IV) was used to prepare three polymers at 5°C. In Example 17 a 1/1 (molar ratio) reaction product of glycidylmethacrylate and p-aminodiphenylamine was used as the monomericantioxidant. In Example 18 a 2/1 (molar ratio) was used. The majorcomponent in each was 3-N-(4'-anilinophenyl)amino-2-hydroxypropylmethacrylate. The polymerization systems were alcohol coagulated,Example 17 at 38.5 percent conversion and Example 18 at 10.0 percentconversion. In Example 19 the monomeric antioxidant was a reactionproduct (2/1 molar ratio) of glycidyl methacrylate andN-phenyl-N'-1,3-dimethylbutyl-p-phenylenediamine. The major componentwas 3-[N-(4'-anilinophenyl)-N-(1,3-dimethylbutyl)]amino-2-hydroxypropylmethacrylate. The polymer of Example 19 was alcohol coagulated at 24percent conversion. Each of the polymerizations was run for 22 hours.

                  Table IV                                                        ______________________________________                                        Order of                                                                      Addition   Ingredients        Parts                                           ______________________________________                                                Water                 180                                                     Linear dodecyl benzene sulfonate                                                                    5                                               1       Sodium salt of condensed                                                      naphthalene sulfonic acid                                                                           .13                                                     Tripotassium phosphate                                                                              0.40                                            2       Acrylonitrile         33                                              3       t-dodecyl mercaptan   0.33                                            4       Monomeric antioxidant 5                                               5       Butadiene-1,3         67                                                      Water                 17                                              6       Chelating agent.sup.(2)                                                                             .075                                                    Sodium formaldehyde sulfoxylate                                                                     .022                                                    FeSO.sub.4.7H.sub.2 O .022                                            7       Cumene hydroperoxide  .056                                                    Benzene               2.4                                             ______________________________________                                    

Table V contains oxygen absorption data for the polymers prepared inExamples 12 to 19.

Before oxygen absorption tests were run on the polymers described inTable V, the dry polymers were extracted for 48 hours with methanol* ina Soxhlet type apparatus to remove any of the free monomeric ageresister and dried. The amount of oxygen absorbed in a particularinterval of time was determined for each sample and is listed in thefollowing Table III. An unstabilized NBR rubber would absorb 1 percentO₂ at 100° C. in less than 10 hours.

                  Table III                                                       ______________________________________                                                     Oxygen Absorption                                                Example      Hours to 1% O.sub.2 at 100°C.                             ______________________________________                                        3            293 and 345                                                      4            385          (to .88% O.sub.2)                                   5            264                                                              6            418                                                              7            393                                                              8            410                                                              9            485                                                              10           410                                                              ______________________________________                                    

The above data demonstrate that the monomeric antioxidants describedherein are capable of providing age resistant polymeric compositions byeither polymerizing the monomeric antioxidants in an emulsion-freeradical polymerization system along with comonomers. That is, the ageresisters provide protection whether in a free or bound condition. Anyof the monomeric antioxidants or polymers described earlier herein canbe substituted for their counterparts in the above working examples toprovide age resistant polymeric compositions.

NBR and SBR polymers were stabilized by physical incorporation of 1.47and 1.25 parts respectively of a reaction product of glycidylmethacrylate and p-aminodiphenylamine (1/1 molar ratio). Both polymerswere stabilized quite effectively.

Naturally polymerization rates and amounts of bound monomer can vary, aswell as the type of emulsifier to be used, depending upon the monomersused. Also, reactor size and degree of agitation can affectpolymerization rates. However, optimum conditions and systems can bedetermined based upon the above revelations by routine experimentationby one possessing ordinary skill in the art. Polymerization rates canoften be improved by using a purified monomeric age resister and/or byraising the polymerization temperature, using more potent initiatorsystems, increasing the initiator level or by any of the conventionalmeans of improving polymerization rates.

All polymer molecular weights referred to herein, unless otherwiseindicated, are number average molecular weights.

The age resistant polymeric compositions prepared by chemically bindingthe antioxidants or by physically incorporating them into polymers, areage resistant, whether in vulcanized or unvulcanized form. They may beused, depending on the particular polymer involved, in products such astires, industrial rubber products, such as transmission belts and hose,and molded goods. Where the polymeric composition contains theantioxidant as an integral part of the polymer chain, it is especiallyuseful in applications where a product is frequently exposed to aqueousdetergent solutions or dry-cleaning fluids, for example, in foambackings for rugs and in polymer treated fabrics.

While certain representative embodiments and details have been shown forthe purpose of illustrating the invention, it will be apparent to thoseskilled in this art that various changes and modifications may be madetherein without departing from the spirit or scope of the invention.

What is claimed is:
 1. A composition of matter comprised of at least onecompound selected from the group consisting of compounds having thefollowing structural formula: ##EQU6## wherein R is selected from thegroup consisting of alkyl radicals having 1 to 12 carbon atoms,cycloalkyl radicals having 5 to 12 carbon atoms, aralkyl radicals having7 to 24 carbon atoms and aryl radicals having 6 to 24 carbon atomswherein R¹ and R² are selected from the group consisting of hydrogen andalkyl groups having 1 to 4 carbon atoms and wherein R³ is selected fromthe group consisting of hydrogen, alkyl radicals having 1 to 12 carbonatoms, cycloalkyl radicals having from 5 to 12 carbon atoms, and aralkylradicals having 7 to 24 carbon atoms, wherein R⁴, R⁵, R⁶, R⁷ and R⁸ areselected from the group consisting of hydrogen and alkyl radicals havingfrom 1 to 4 carbon atoms, and wherein R⁹ and R¹⁰ are selected from thegroup consisting of hydrogen and alkyl radicals having from 1 to 4carbon atoms.
 2. The composition according to claim 1 wherein -NH-R isin the para position.
 3. The composition according to claim 1 whereinthe sum of the carbon atoms in R⁴ and R⁵ are 4 or less and wherein thesum of carbon atoms in R⁷ and R⁸ are 4 or less.
 4. The compositionaccording to claim 1 wherein R⁸ is selected from the group consisting ofhydrogen and methyl and R⁹ is hydrogen.
 5. The composition according toclaim 1 wherein R¹¹ and R¹² are selected from the group consisting ofmethyl and ethyl radicals.
 6. The composition according to claim 1wherein the composition is 3-N-(4'-anilinophenyl)amino-2-hydroxypropylmethacrylate.